Dopamine-Beta-hydroxylase (DBH) is the enzyme which catalyzes the conversion of dopamine to norepinephrine in noradrenergic neurons. We are measuring DBH in human cerebrospinal fluid, and the amount of this enzyme is taken as an index of central noradrenergic activity. Subjects are psychiatric patients who have been hospitalized for schizophrenia, affective illness, alcoholism, or personality disorders. Preliminary data indicate that DBH tends to be low in CSF from schizophrenic patients, and that DBH levels in cerebrospinal fluid from patients with affective illness are related to the clinical symptoms of disease.